Apparatus for temporarily connecting together perforated flat parts, such as metal sheets



I 2,790,346 c'rmc TOGETHER H AS METAL s Filed Sept. 30, 1955 HEETS April 30, 1957 w. REINIGER APPARATUS FOR TEMPORARILY CONN PERFORATED FLAT PARTS, SUC

United States Patent APPARATUS FOR TEMPORARILY CONNECTING TOGETHER PERFORATED FLAT PARTS, SUCH AS METAL SHEETS Waldemar Reiniger, Schorndorf, Wurttemberg, Germany, assignor to Waggon und Maschinenbau G. in. b. H., Donauworth, Germany Application September 30, 1955, Serial No. 537,867

4 Claims. (Cl. 85-6) The present invention relates to apparatus for temporarily connecting to each other perforated flat parts, such as metal sheets, each having holes adapted to register with the corresponding holes in another for receiving permanent connecting means, such as rivets or the like.

Known apparatus of this kind includes a mandrel which fits into the holes and may be pushed out of the base of a sleeve or cup against the resistance of a helical spring encircling the mandrel and which reacts against an abutment secured to the rear of the mandrel. The base of the said sleeve is used as a guide for the mandrel and also as a pressure member which abuts on one outer side of the parts to be connected for as long as the temporary connection is effective. The mandrel is provided with a diametral longitudinal slot receiving a locking member which is formed by a spring wire bent U- shaped as in a hair pin. One limb of this U-shaped locking member is curved in the form of a hook and is hooked over the end coil of the said helical spring adjacent the base of the sleeve, while the other and longer limb is disposed against a steep inclined surface which limits the said longitudinal slot in the mandrel and extends towards the point thereof.

With the mandrel in an advanced position relatively to the sleeve, the extremity of the long limb of the spring locking wire is Withdrawn into the profile of the mandrel.

In order to introduce the mandrel into the perforations of the parts to be temporarily connected, said mandrel is first pushed forward out of the base of the sleeve against the resistance of the helical spring far enough for the end of the long limb of the spring locking wire to retreat into the profile of the mandrel. After said mandrel is passed through the holes far enough for the base of the sleeve to abut the adjacent face of one of the parts to be connected, the mandrel is then allowed to retreat into the sleeve by partly releasing the helical spring until the end of the longer limb of the spring locking wire again projecting out of the side of the mandrel, sufliciently to act as a stop on the outer face of the other of the parts being connected, and by its obstructing further thereby withdrawal of the mandrel ensures a temporary connection together of the said parts under the remaining tension of the helical spring.

The object of the present invention is to improve temnection of two perforated sheets;

porary connection devices of this kind to make their op- Fig. 2 shows the same apparatus, likewise as a longitudinal section, but with the mandrel greatly advanced,

that is to say, in a primed position ready for the insert-- ing of the mandrel into the holes of parts to be connected;

Fig. 3 shows the wire spring locking member alone, formed by a two-limbed spring wire, in unstressed condition; and I Fig. 4 is a plan of the upper end of the apparatus, projected from Fig. 1.

As shown, the apparatus consists of a cylindrical sleeve 1, closed at the base 2 which is somewhat inwardly curved and has a central circular opening for guiding the cylindrical mandrel 3. The mandrel has at its front or outer end a point 4 and, at its rear or outer end, an annular groove .5 in which the base 6 of a cup 7 is engaged, the peripheral wall of this cup being guided in the open end of the sleeve 1. This cup 7 forms the rear abutment for a helical wire spring 8 which surrounds the mandrel 3, and the other end of which abuts the base 2 of the sleeve 1.

The head 9 of the mandrel 3, projecting beyond the base 6 of the cup 7 is flattened at two opposite sides, see Fig. 4. In the base 6 of the cup 7 is disposed at corresponding flat-sided slot or perforation 10 which permits the passing through of the head 9 when the axis of such head is in register with the axis of the slot. After turning the head 9 of the mandrel through it rests in two depressions 11 and 12 provided on the outside of the base 6. Alternatively, the rear end of the mandrel 3 may be tightly riveted or otherwise secured to the base 6 of the cup.

The base 2 is formed in one piece with the cylindrical jacket of the sleeve 1, for example by deep drawing from sheet metal. The jacket of the sleeve is long enough for it to receive and axially guide the cup 7 in any operative position of the mandrel. The edge 13 of the jacket of the sleeve is flanged or rolled on the outside and forms an annular abutment for one jaw of a known operating tool (not shown) the other jaw of which tool presses on the base 6 of the cup 7 and permitting the closing of the jaws to push the mandrel forward for example into the position shown in Fig. 2.

In the mandrel 3 is disposed at diametral slot 14 which is limited at the lower end by the steep inclined surface 15 extending towards the point 4 of the mandrel. In the slot 14 is disposed the locking member 16 which is formed by a length of spring wire shaped substantially in the form of a hair pin. One limb 17 of the locking member has a return curve in the form of a parallelsided hook and thereby engages the lowest turn of the helical spring 8. Preferably the said hook is long enough to engage at least two turns of the helical spring 8 and thereby stiffen the shorter limb against deflection while the longer limb is deflected and tensioned. The apex of the locking member 16 has an enlarged bulge 18 which is off-set towards the side of the long straight limb 19, the end of which limb 19projects out of the side of the mandrel 3 when the parts are in the position shown in Fig. 1 and serves as an abutment to retain the sheets being held together.

The steep inclined surface 15 at the bottom of said slot 14 is so arranged between the shanks 17 and 19 of the locking spring that it is remote from the hook-shaped part 17 of the locking member. That is to say the part 17 is at the side of the mandrel 3 which is behind the inclined surface 15. Consequently, when the helical pressure spring 8 is released, that is to say, when the mandrel returns into the sleeve, the long limb 19 of the spring wire is bent up by the inclined surface 15 sliding below it and thereby such limb 19 is placed under tension. The

inclined surface provided according to this invention is oppo s edtotliat in the hitherto known devices. i

The method of using andoperating the device is as follows:

First the mandrel 3 is broughtinto. the position shown in Fig. 2 bypressureon. its head 9 and ,onrthe base 6 of the cup,,-against .the resistan'cebfthe spring 8. At the same time the extremity of the limb 19 of the spring wire slides upwardly on the inclinedsurface 1S and cornpletely retreats into the slot 14 of the mandrel 3, as shown in Fig. 2, because the two limbs 17 and 19, being stressed, tend to return into the unstressed position shown in Fig. 3, in which position they touch or almost touch each other at the parts 20 and 21.

In the position shownin Fig. ,l the limbs ofthe locking member :16 are subjected tofa separating effect by the actionof the inclined surface 15 pressing on the limb 19. This-prevents undesired pivoting of the locking member about its engagement'with thelowest turn of the helical spring Sand guards against any undesired disengagement of the end of the limb 19 from the slot 14.

The apparatus may therefore, when in the position shown inFig. 2, be passed through the mutually corresponding perforations of two superimposed sheets 22 and 23 until the base 2 of the sleeve 1, acting as a pressure member, abuts one sheet 22, as shown in Fig. 1. Then the mandrelis allowed to retract automatically into the sleeve 1, under the partial release of the spring 8, the limb 1 advancing more and more out of the slot 14 by its deflection due to the movement of the inclined surface 15 on which the extremity of the limb 19 slides down, until the portion projecting from the side of the mandrel comes in contact with the sheet 23 as astop. In this position, shown in Fig. 1, the two sheets 22 and 23 are temporarily'held together between the laterally projecting end of the limb 19 and the base 2 of the sleeve 1, under the residual pressure of the spring 8, so that permanent connections, for example rivets, can be made at other points on the two sheets, with the sheets in the correct position relatively to one another.

For extracting the apparatus, the mandrel 3 is first advanced asfar as the position shown in Fig. 2, so that the spring limb 19 is entirely within the mandrel whereupon the apparatus can be withdrawn from the holes in the sheets 22 and 23, and eventually relaxed.

I claim:

1. A device for temporarily clamping perforated parts together comprising a sleeve open at one end and having an aperture in the other end, a mandrel slidable in said aperture and including a body and a head slidable in said sleeve, said mandrel body being provided with a diametrical'slothavin'g'a steeply inclined surface at its lowerehd, said inclined surface forming an acute angled edge with the circumferential surface of said mandrel, a compression spring between the aperture-provided end of the sleeve and the mandrel head, and a locking element formed substantially hair-pin-likefrom apieceof resilient wire, said element havingone longer and. one shorter limb and straddling said edge with, said "limbs zwhenjsaid mandrel is in a retracted position, said longer limb lying on said inclined surface, said shorter limb being anchored by said compressionspring in said-sleeve at'the side .iof the mandrel remote from said inclined surface, said longer limb being in permanent engagfiment with said inclined surface and being stressed thereby between a minimum when the mandrel is projected from said aperture against the restraint of said spring and said longer limb is fully withdrawn into said slot and a 'maximum. when the mandrel is retracted intothe sleeve and said ilonger limb partly projectsfrom said slot on the side of said mandrel opposite saidshorter limb.

2. A device as:in claim 1 wherein said longer limb is straight and said shorter limb U-shaped and located inside said sleeve, at least two turns of said compression spring engaging in said U-shaped limb;

3. A'devicefas in ,claim 1, said longer, limb being Straight an saidfl horter, limb being U-shaped and hooked underneathsaid jcomp icssion springso as to receive in said U-jshape at leasttwo convolutions of said compression spring, said locking element further including an enlarged bulge at the apex of the limbs, said bulge being located within said slot andfbeing ofi-set above the longer limb, the two limbs as originally bentin unstressed condition beingin close proximity of each other.

4. A device as in claim,1,;wherein saidhead of-said mandrel is of inverted cup-shape and the mandrel body has a fiat-sidedend projecting exteriorly of the cup-shaped mandrel head, saidhead having a slot to allow passage of the flat-sidedendtherethrough, and depressions toree ceive the passed-through end after being turned through 7 References Cited in the file of this patent UNITED STATES PATENTS 2,271,879 Wallace Feb. 3, 1942 2,230,403 Finkle Apr. 21, 1942 2,343,499 Edwards Mar. 7, 1944 FOREIGN PATENTS 52,527 France Apr. 17, 1945 

